Method of arc welding



Nov. 5, 1940. M. H. MaoKUSlCK 2,220,576

METHOD OF ARC WELDING Original Filed July 1, 1936 I NVENTOR.

Meredith H. MacKusick ATTORNEY.

Patented Nov. 5, 1940 UNITED STATES PATENT OFFICE METHOD OF ARC WELDINGContinuation of application Serial No. 88,311, July 1, 1936. Thisapplication August 13, 1938,

Serial No. 224,818

3 Claims.

This invention is a method of performing automatic electric arc depositof. weld metal at high rates of deposition, the resulting union beinfree of cracks, high in density with a minimum 5 of contamination, andwithout material detraction from the physical and chemical properties ofthe parent metal, or from the original metal from which the deposit islaid down.

It has been, and now is, the custom in automatic electric arc welding toform an arc between an upright weldrod and the work piece in a manner todeposit metal from the weldrod integrally with the work piece, andvarious means have been resorted to, such as covered weldrods, gasenvelopes, powdered fluxes and the like to eiiectively shield the arefrom the at mosphere so that inclusions of oxides and nitrogencompounds, and detraction from the physical and chemical properties ofthe parent metal, as well as that of the deposit may be reduced to aminimum.

Also it has been the practice to feed the weldrod toward the arc andregulate the current characteristics in a manner to produce a uni- 5form rate 05 deposit, but such apparatus is complicated and thesensitivity of the arc is not equally reflected in the mechanism fortheweldrod feeding and hence thereis a hunting effect as to the arclength with the result that it is difilcult to secure uniform results,especially with metal work of one-half inch thickness and greater, andalso the rates of deposit to secure good results are necessarily slowwith a consequent high cost per pound of sound weld metal deposited,thus materially adding to the cost of fabricating welded articles.

It has more recently been proposed, in the prior art, to lace a coveredweldrod horizontally along, or parallel with, a butted seam, start theare at one end of the weldrod and permit it to be consumed while keepinga current feeding contact in contact with a bare portion of the rod inadvance of the arcing and thereof by a step-by-step movement along thebare portion which is on the upper side, but such method and apparatushave not been entirely satisfactory due to the fact that the covered rodinterposes difliculties in that there is an ever changing condition ofthe are due to the character of the coverings which are non-conductorsand usually have a detrimental influence on an are so far as maintaininguniformity throughout the run, and then too the weldrod is above theseam and has a portion bared of covering and which cannot be adequatelyshielded unless a second The present invention is an improvement onknown methods in that it provides for disposing a bare weldrod, withconsequent uniformity of electrical characteristics, within, or at leastpartially within a narrow welding groove in the work piece instead of ontop of it and temporarily insulated from the work piece by meansconsumed by the are as it deposits the metal of the weldrod and whichmay be simply an insulator or may contribute a desirable influence tothe operation.

Additionally, the invention contemplates a completely smothered are, asdistinguished from the shielded arc of the prior art such as is soughtwith covered rods of the slag forming and gas forming variety; and withthis invention the arc and resultant metal pool are, throughout theoperation, entirely hidden from view and completely shielded by asmothering agency which, in addition to positively excluding oxygen andnitrogen of the air, conceals the are from view and hence does away withthe necessity for unusual protection of the operators eyes.

Also, by reason of using a bare metal weldrod control of the arc isreadily established by a set of predetermined conditions insuring afixed arc length throughout the run with the result that weldrods oflarger diameter with heavier current densities may be used withconsequently greater rate of deposition of sound weld metal at a lowercost per unit length of weld than has heretofore been possible,coincident with uniformly better results.

In using the present invention welding speeds of 60 to 100 feet per hourare attainable with single bead deposit, and the chemical analyses ofweld deposited metal reveals that the protection from atmosphericcontamination is such that a carbon content is obtained in the weldmetal which is approximately twice that obtainable with standard priorart methods, and, furthermore, the weld is free of cracks and-with aminimum of nitrogen content.

In the drawing accompanying this specification there are illustratedseveral methods and apparatus for performing the present invention, and

Fig. 1 is a perspective view of the assembly of the work pieces, weldingstrip and contact without the smothering agent applied, but with theparts tilted at an angle to maintain only a small horizontal pool ofmolten metal;

Fig. '2 is a similar view, partly in section;

Fig. 3 is an end view in section of a cylindrical drum mounted forrotation and for welding a groove seam;

Fig. 4 is a transverse section through work pieces and weldrod preparedfor welding by the smothered arc method;

Fig. 5 is a view similar to Fig. 4 of another method of assembly;

Fig. 6 is a view similar to Fig. 5 showing how a thin weldrod strip isused;

Fig. 7 is a view similar to Figs. 4, 5 and 6 showing the use of a roundweldrod;

Fig. 8 is a typical longitudinal section on line 8--8 of Fig. 4; and

Fig. 9 is a view, partly diagrammatic, showing the manner of concealingan arc smothered with gas as an oxygen inhibiter.

Referring in detail to the drawing; Fig. 1 il lustrates the work piecesI and 2 which have their sides chamfered or grooved to provide lips 3and 4 which are brought in proximity but not quite touching and having abacking-up strip 5 applied to the bottom side thereof. A welding strip 6of oval form is then fitted into the seam groove thus provided and, asshown, is supported by insulators l at spaced intervals therealong.These insulator may be of any suitable material, such, for instance, asmica, and are of a thickness selected in accordance with the size of therod to be used, the character of the metal to be welded, and the currentvalues to be used. They serve to maintain a fixed arcing distancebetween the parent metal work pieces I and 2 and the welding strip. Atthe top side of the work pieces I and 2 are two longitudinal members 8and 9 spaced apart and tack welded or otherwise secured, and whichserve, as will be later described, to provide a receiving trough forpulverulent arc smothering material such, for instance, as a mixture ofAt the upper side of the welding strip 6 is a contact member ID, thiscontact member and the work, including the welding strip, being movedrelatively at a rate commensurate with the rate of deposition calculatedfrom the value of current used and the size of the weldrod employed.

There is illustrated in Fig. 2a partially compl-eted weld, the completedportion being indicated at II. This portion is overlaid with a coveringof slag l2 formed from the fusion of the smothering flux material l3which is fed through the spout H in a regulated manner as by a valve l5(see Fig. 3) between the arcing end of the weldrod 6 and the contactmember I0 and in sufficient quantity to substantially fill the spacebetween the members 8 and 9 and completely smother the are from view,thereby excluding the atmosphere. After the completion of the weld,which may be made by a single traverse of the contact member ID, or maybe made by use of subsequent weldrods 6 similarly placed, the backing-upstrip 5 may be removed by chipping, or the like, and a wash welddeposited.

In Fig. 4 there are shown two work pieces l6 and I! having lips I8 andI9 closed on the under side by a backing-up strip and with a rectangularwelding strip 2| placed in the groove and insulated therefrom by theinsulating means 22 which may be either of the intermittent strip type,as shown in Figs. 1 or 2, or may be a full strip, if desired. Thiswelding strip 2| is proportioned to stand sufficiently above the surfaceof the surrounding metal l6 and I1, and, as it is fused into place ittakes care of filling the groove regardless of the interposition of theinsulating material 22 which is burned away, or consumed during theprocess. The same is similarly true of the types shown in Figs. 5, 6 and7 which simply are different forms and consequently bear the samereference numerals as do Fig. 4.

In Fig. 3 a circular drum is shown with the apparatus prepared forwelding a circumferential groove seam. In this instance the contactmember ID is located at the top of the apparatus and immediately inadvance of it is the delivery spout [4 with its valve l5 for depositingthe required quantity of pulverulent slag-forming or otherarc-smothering and fiuxing material. The members 8 and 9 confining thefiuxing material, in this instance, are tack welded to the bodystructure and are circular in form. The welding rod or strip 6 is madein halves joined together by tack welding, or the like, as at 23, andthe starting end 24 is separated from the finishing end by a very smalldistance, but the finishing end has welded thereto a strip or tang 25which is bent upwardly, as shown, so that in the final position thewelded contact 10 may ride thereupon; this end is insulated from thecylindrical body portion by the bridge member 26 which spans the seamgroove, The total cylindrical structure rests upon rollers 21, one ofwhich is provided with a pulley 28 belted as at 29 to the pulley 30 ofthe motor 3| for driving in the manner to be hereinafter described inconnection with Fi 9. I

Now with reference to Fig. 9 there is here shown a cylindrical bodysimilar to that indicated in Fig. 3 but with the apparatus arranged witha hood 32 accommodating the contact member l0 and receiving a supply ofgas 33 instead of a solid flux. This hood completelyencloses the arc andremains stationary while the cylindrical work piece is revolved in themanner as described in connection with Fig. 3. However, the rate of Incarrying out the invention, while I have described one form ofaccomplishing relative movement between contact l0 and the work, asshown in Fig. 3, numerous others may be resorted to, as for instance thecontact l0 and attendant flux distributor may be moved by a lead screw,or the work may be moved by a lead screw.

Also the powdered flux may be placed over the weldrod and groovethroughout the entire length and the contact [0 shaped, as shown, toplow through such flux.

It is preferable to keep the groove narrow in comparison with its depth.Weldrods 0f x A" oval have been satisfactorily used in welding platewith a groove depth of by A" width and with 1100 amperes, and, as beforestated, in single bead deposition welding speeds of 60 to 100 feet perhour have been attained.

This application is a continuation of application No. 88,311, filed onJuly 1, 1936,

While in the foregoing specific features and steps have been describedin connection with my invention, it is nevertheless to be understoodthat I do not limit myself thereto except as the appended claims definethe invention in its broadest sense over the prior art.

I claim:

1. The method of arc welding grooved work which comprises sustaining awelding strip lengthwise of the groove in an insulating manner and inuniformly spaced relation to the groove walls throughout the length ofthe strip and with a substantial area of the strip in cross sectiondisposed within the groove, including the work and strip in a weldingcircuit, and promoting an are between an end of the strip and the workwhereby the strip is progressively deposited with an arc confinedsubstantially to the area of the end of the welding strip.

2. In a method of fusion welding, juxtaposing workpieces so as to definethe sides of a welding groove, fitting a metallic weld strip in thegroove and longitudinally thereof with a substantial portion of its bodywithin the cross-sectional confines of the groove and the remainderexternally of the groove, maintaining the weld strip electricallyinsulated from the workpieces and substantially uniformly spaced fromthe walls of the groove, covering at least a complete transverse sectionof the weld strip and the weld groove in the welding zone with fluxingmaterial so that the electric arc is smothered during the weldingoperation, including the strip and the work in an electric weldingcircuit with an electric terminal in contact with the weld strip,establishing an arc between the workpieces and the weld strip, andcausing the terminal to move along the weld strip and through thefiuxing material as the weld strip is fused and the weld formed.

3. A fusion welding method which comprises the juxtapositioning ofworkpieces so as to define the sides of a welding groove, fitting a baremetal weld strip in the groove and longitudinally thereof with asubstantial portion of its body within the cross sectional confines ofthe groove and a portion externally thereof sufficient to complete thefilling of the groove when the weld is completed and simultaneouslyinsulating the weld strip from the workpieces and thereby maintainingthe weld strip substantially uniformly spaced from the groove walls,establishing electrical contact between a welding circuit terminal andthe strip, establishing an electric arc between the weld strip and theworkpieces by completing a welding circuit through the weld strip andthe workpieces, effecting relative movement between the weld strip andthe welding circuit terminal in contact with the strip longitudinally ofthe groove, and simultaneously and synchronously elfecting a progressivecovering at least a complete section of the weld strip and the grooveand filling the arcing space by the deposition of fiowable fluxingmaterial which completely smothers the arc, and retaining the fluxingmaterial in such covering and filling relationship.

MEREDITH H. MACKUSICK.

